Hook up the SequencedWorkerPool to the browser thread.

[re-land of 116816 http://codereview.chromium.org/9065009]

This does some refactoring of the static data in the browser thread so we only have one global object instead of a bunch fo separate arrays.

It also hooks up the visited link master's I/O to use this new system as a proof of concept.
Review URL: https://chromiumcodereview.appspot.com/9124033

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@118236 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 21 insertions, 12 deletions

diff --git a/chrome/browser/visitedlink/visitedlink_master.cc b/chrome/browser/visitedlink/visitedlink_master.cc
index f3fbc85..38c87ca 100644
--- a/chrome/browser/visitedlink/visitedlink_master.cc
+++ b/chrome/browser/visitedlink/visitedlink_master.cc
@@ -191,6 +191,7 @@ void VisitedLinkMaster::InitMembers(Listener* listener, Profile* profile) {
   history_service_override_ = NULL;
   suppress_rebuild_ = false;
   profile_ = profile;
+  sequence_token_ = BrowserThread::GetBlockingPool()->GetSequenceToken();
 
 #ifndef NDEBUG
   posted_asynchronous_operation_ = false;
@@ -242,6 +243,12 @@ VisitedLinkMaster::Hash VisitedLinkMaster::TryToAddURL(const GURL& url) {
   return AddFingerprint(fingerprint, true);
 }
 
+void VisitedLinkMaster::PostIOTask(const tracked_objects::Location& from_here,
+                                   const base::Closure& task) {
+  BrowserThread::GetBlockingPool()->PostSequencedWorkerTask(sequence_token_,
+                                                            from_here, task);
+}
+
 void VisitedLinkMaster::AddURL(const GURL& url) {
   Hash index = TryToAddURL(url);
   if (!table_builder_ && index != null_hash_) {
@@ -480,10 +487,7 @@ bool VisitedLinkMaster::WriteFullTable() {
               hash_table_, table_length_ * sizeof(Fingerprint));
 
   // The hash table may have shrunk, so make sure this is the end.
-  BrowserThread::PostTask(
-      BrowserThread::FILE,
-      FROM_HERE,
-      base::Bind(base::IgnoreResult(&TruncateFile), file_));
+  PostIOTask(FROM_HERE, base::Bind(base::IgnoreResult(&TruncateFile), file_));
   return true;
 }
 
@@ -673,11 +677,7 @@ void VisitedLinkMaster::FreeURLTable() {
   }
   if (!file_)
     return;
-
-  BrowserThread::PostTask(
-      BrowserThread::FILE,
-      FROM_HERE,
-      base::Bind(base::IgnoreResult(&fclose), file_));
+  PostIOTask(FROM_HERE, base::Bind(base::IgnoreResult(&fclose), file_));
 }
 
 bool VisitedLinkMaster::ResizeTableIfNecessary() {
@@ -860,9 +860,7 @@ void VisitedLinkMaster::WriteToFile(FILE* file,
 #ifndef NDEBUG
   posted_asynchronous_operation_ = true;
 #endif
-
-  BrowserThread::PostTask(
-      BrowserThread::FILE, FROM_HERE,
+  PostIOTask(FROM_HERE,
       base::Bind(&AsyncWrite, file, offset,
                  std::string(static_cast<const char*>(data), data_size)));
 }
diff --git a/chrome/browser/visitedlink/visitedlink_master.h b/chrome/browser/visitedlink/visitedlink_master.h
index c84e809..1771afe 100644
--- a/chrome/browser/visitedlink/visitedlink_master.h
+++ b/chrome/browser/visitedlink/visitedlink_master.h
@@ -17,6 +17,7 @@
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/shared_memory.h"
+#include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/history/history.h"
 #include "chrome/common/visitedlink_common.h"
 
@@ -163,6 +164,10 @@ class VisitedLinkMaster : public VisitedLinkCommon {
   // File I/O functions
   // ------------------
 
+  // Posts the given task to the blocking worker pool with our options.
+  void PostIOTask(const tracked_objects::Location& from_here,
+                  const base::Closure& task);
+
   // Writes the entire table to disk, returning true on success. It will leave
   // the table file open and the handle to it in file_
   bool WriteFullTable();
@@ -312,6 +317,9 @@ class VisitedLinkMaster : public VisitedLinkCommon {
   // (it knows the path to where the data is stored)
   Profile* profile_;
 
+  // Lazily initialized sequence token for posting file tasks.
+  base::SequencedWorkerPool::SequenceToken sequence_token_;
+
   // When non-NULL, indicates we are in database rebuild mode and points to
   // the class collecting fingerprint information from the history system.
   // The pointer is owned by this class, but it must remain valid while the
diff --git a/chrome/browser/visitedlink/visitedlink_unittest.cc b/chrome/browser/visitedlink/visitedlink_unittest.cc
index 2d52cb0..536384f 100644
--- a/chrome/browser/visitedlink/visitedlink_unittest.cc
+++ b/chrome/browser/visitedlink/visitedlink_unittest.cc
@@ -116,6 +116,9 @@ class VisitedLinkTest : public testing::Test {
       // our destroy task.
       MessageLoop::current()->Run();
     }
+
+    // Wait for all pending file I/O to be completed.
+    BrowserThread::GetBlockingPool()->FlushForTesting();
   }
 
   // Loads the database from disk and makes sure that the same URLs are present